fix: duplicate background tasks

crates/rustmail/src/commands/add_reminder/common.rs

@@ -5,7 +5,7 @@ use chrono::Local;
 use serenity::all::{ChannelId, CommandInteraction, Context, GuildId, Message, RoleId, UserId};
 use sqlx::SqlitePool;
 use std::collections::{HashMap, HashSet};
-use std::sync::Arc;
+use std::sync::{Arc, LazyLock};
 use std::time::Duration;
 use tokio::select;
 use tokio::sync::watch::Receiver;
@@ -109,6 +109,9 @@ pub async fn send_register_confirmation_from_command(
         .await;
 }
 
+/// One timer per reminder id.
+static REMINDER_TIMERS: LazyLock<KeyedTasks<i64>> = LazyLock::new(KeyedTasks::new);
+
 pub fn spawn_reminder(
     reminder: &Reminder,
     reminder_id: Option<i64>,
@@ -123,7 +126,7 @@ pub fn spawn_reminder(
     let reminder = reminder.clone();
     let mut shutdown_rx = shutdown.as_ref().clone();
 
-    tokio::spawn(async move {
+    REMINDER_TIMERS.spawn(reminder.id, async move {
         let now = Local::now().timestamp();
         let delay_duration = if reminder.data.trigger_time > now {
             reminder.data.trigger_time - now

crates/rustmail/src/commands/delete/common.rs

@@ -82,7 +82,7 @@ pub async fn delete_dm_message(ctx: &Context, user_id: i64, message_ids: &Messag
     if let Some(dm_msg_id) = &message_ids.dm_message_id
         && let Ok(msg_id) = dm_msg_id.parse::<u64>()
     {
-        if let Ok(user) = ctx.http.get_user(UserId::new(user_id as u64)).await {
+        if let Ok(user) = UserId::new(user_id as u64).to_user(ctx).await {
             if let Ok(dm_channel) = user.create_dm_channel(&ctx.http).await {
                 match dm_channel.message(&ctx.http, msg_id).await {
                     Ok(dm_message) => {

crates/rustmail/src/commands/new_thread/slash_command/new_thread.rs

@@ -112,7 +112,7 @@ impl RegistrableCommand for NewThreadCommand {
                 }
             };
 
-            let user = match ctx.http.get_user(user_id).await {
+            let user = match user_id.to_user(&ctx).await {
                 Ok(user) => user,
                 Err(_) => return Err(ModmailError::Discord(DiscordError::UserNotFound)),
             };

crates/rustmail/src/commands/new_thread/text_command/new_thread.rs

@@ -28,7 +28,7 @@ pub async fn new_thread(
 
     let user_id = user_id.unwrap();
 
-    let user = match ctx.http.get_user(user_id).await {
+    let user = match user_id.to_user(&ctx).await {
         Ok(user) => user,
         Err(_) => return Err(ModmailError::Discord(DiscordError::UserNotFound)),
     };

crates/rustmail/src/commands/release/slash_command/release.rs

@@ -97,12 +97,11 @@ impl RegistrableCommand for ReleaseCommand {
                             }
                         };
                         ticket_status.taken_by = None;
-                        let _ = update_thread_status_db(
-                            &thread.id.to_string(),
-                            &ticket_status,
-                            &db_pool,
-                        )
-                        .await;
+                        if let Err(e) =
+                            update_thread_status_db(&thread.id, &ticket_status, &db_pool).await
+                        {
+                            eprintln!("Failed to update thread status for {}: {e:?}", thread.id);
+                        }
 
                         let applied = update_thread_status_ui(&ctx, &ticket_status)
                             .await

crates/rustmail/src/commands/release/text_command/release.rs

@@ -50,7 +50,10 @@ pub async fn release(
                     }
                 };
                 ticket_status.taken_by = None;
-                let _ = update_thread_status_db(&thread.id, &ticket_status, &db_pool).await;
+                if let Err(e) = update_thread_status_db(&thread.id, &ticket_status, &db_pool).await
+                {
+                    eprintln!("Failed to update thread status for {}: {e:?}", thread.id);
+                }
 
                 let applied = update_thread_status_ui(&ctx, &ticket_status)
                     .await

crates/rustmail/src/commands/rename/slash_command/rename.rs

@@ -110,7 +110,11 @@ impl RegistrableCommand for RenameCommand {
                     };
 
                     ticket_status.label = new_label.clone();
-                    let _ = update_thread_status_db(&thread.id, &ticket_status, &db_pool).await;
+                    if let Err(e) =
+                        update_thread_status_db(&thread.id, &ticket_status, &db_pool).await
+                    {
+                        eprintln!("Failed to update thread status for {}: {e:?}", thread.id);
+                    }
 
                     let has_label = new_label.is_some();
                     let applied = update_thread_status_ui(&ctx, &ticket_status)

crates/rustmail/src/commands/rename/text_command/rename.rs

@@ -46,7 +46,9 @@ pub async fn rename_ticket(
                 ticket_status.label = Some(new_label.clone());
             }
 
-            let _ = update_thread_status_db(&thread.id, &ticket_status, &db_pool).await;
+            if let Err(e) = update_thread_status_db(&thread.id, &ticket_status, &db_pool).await {
+                eprintln!("Failed to update thread status for {}: {e:?}", thread.id);
+            }
 
             let has_label = ticket_status.label.is_some();
             let applied = update_thread_status_ui(&ctx, &ticket_status)

crates/rustmail/src/commands/take/slash_command/take.rs

@@ -98,7 +98,11 @@ impl RegistrableCommand for TakeCommand {
                             }
                         };
                         ticket_status.taken_by = Some(command.user.id.to_string());
-                        let _ = update_thread_status_db(&thread.id, &ticket_status, &db_pool).await;
+                        if let Err(e) =
+                            update_thread_status_db(&thread.id, &ticket_status, &db_pool).await
+                        {
+                            eprintln!("Failed to update thread status for {}: {e:?}", thread.id);
+                        }
 
                         let applied = update_thread_status_ui(&ctx, &ticket_status)
                             .await

crates/rustmail/src/commands/take/text_command/take.rs

@@ -49,7 +49,10 @@ pub async fn take(
                     }
                 };
                 ticket_status.taken_by = Some(msg.author.id.to_string());
-                let _ = update_thread_status_db(&thread.id, &ticket_status, &db_pool).await;
+                if let Err(e) = update_thread_status_db(&thread.id, &ticket_status, &db_pool).await
+                {
+                    eprintln!("Failed to update thread status for {}: {e:?}", thread.id);
+                }
 
                 let applied = update_thread_status_ui(&ctx, &ticket_status)
                     .await

crates/rustmail/src/db/operations/init.rs

@@ -28,7 +28,10 @@ pub async fn init_database() -> Result<SqlitePool, sqlx::Error> {
         .busy_timeout(Duration::from_secs(5));
 
     let pool = SqlitePoolOptions::new()
-        .max_connections(30)
+        // SQLite has a single writer; extra connections only add lock contention.
+        .max_connections(10)
+        // Fail fast instead of piling up callers for 30s when the pool is exhausted.
+        .acquire_timeout(Duration::from_secs(10))
         .connect_with(connect_options)
         .await?;
 

crates/rustmail/src/db/operations/messages.rs

@@ -26,7 +26,7 @@ pub async fn insert_staff_message(
     let user_id = staff_user_id.get() as i64;
 
     let user_name = staff_user_id
-        .to_user(&ctx.http)
+        .to_user(ctx)
         .await
         .map(|user| user.name)
         .unwrap_or_else(|_| "Unknown".to_string());
@@ -273,7 +273,7 @@ pub async fn insert_internal_message(
     let user_name = msg
         .author
         .id
-        .to_user(&ctx.http)
+        .to_user(ctx)
         .await
         .map(|user| user.name)
         .unwrap_or_else(|_| "Unknown".to_string());